为深入探讨氮沉降影响草原植物金属养分吸收及其与土壤养分的耦合关系,以内蒙古典型草原4种主要物种为研究对象,设置0、5、10、15 g N/(m^(2)·yr)4个氮添加处理,分析不同施氮量对草原物种及群落水平植物叶片盐基、微量元素含量和...为深入探讨氮沉降影响草原植物金属养分吸收及其与土壤养分的耦合关系,以内蒙古典型草原4种主要物种为研究对象,设置0、5、10、15 g N/(m^(2)·yr)4个氮添加处理,分析不同施氮量对草原物种及群落水平植物叶片盐基、微量元素含量和储量的影响。结果表明:(1)杂类草比禾本科植物具有更高的养分浓度;(2)不同金属养分对氮沉降的响应具有高度的物种特异性;植物群落叶片盐基元素含量对氮添加无显著响应且与土壤盐基离子相关性较低;随氮添加量的增加,叶片中Mn、Cu含量增加,但Fe含量降低,草原植物微量元素失衡严重主要受土壤微量养分有效性和元素拮抗作用的影响;(3)植物金属元素地上储量的饱和阈值出现在10 g N/(m^(2)·yr);优势物种地上生物量对氮添加的非线性响应是驱动植物元素地上储量变化的主要机制。展开更多
Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing e...Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon （SOC） and soil total nitrogen （STN） storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass （AGB）, belowground biomass （BGB）, SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation （MAP）. Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer （10 cm） after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversitv conservation.展开更多
文摘为深入探讨氮沉降影响草原植物金属养分吸收及其与土壤养分的耦合关系,以内蒙古典型草原4种主要物种为研究对象,设置0、5、10、15 g N/(m^(2)·yr)4个氮添加处理,分析不同施氮量对草原物种及群落水平植物叶片盐基、微量元素含量和储量的影响。结果表明:(1)杂类草比禾本科植物具有更高的养分浓度;(2)不同金属养分对氮沉降的响应具有高度的物种特异性;植物群落叶片盐基元素含量对氮添加无显著响应且与土壤盐基离子相关性较低;随氮添加量的增加,叶片中Mn、Cu含量增加,但Fe含量降低,草原植物微量元素失衡严重主要受土壤微量养分有效性和元素拮抗作用的影响;(3)植物金属元素地上储量的饱和阈值出现在10 g N/(m^(2)·yr);优势物种地上生物量对氮添加的非线性响应是驱动植物元素地上储量变化的主要机制。
基金Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060700)Postdoctoral Science Foundation of China(No.2013M530716)
文摘Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon （SOC） and soil total nitrogen （STN） storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass （AGB）, belowground biomass （BGB）, SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation （MAP）. Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer （10 cm） after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversitv conservation.
